Floating roof for liquid storage tanks



Aug. 30, 1932. J. H. WIGGINS FLOATING ROOF FOR LIQUID STORAGE TANKS Filed April 5. 1929 Patented Aug. .30, 1932 UNITED STA JOHN H. WIGGINS, OFTULSA, OKLAHOMA FLOATING RO OF FOR LIQUID STORAGE TAN KS Application filed April 8, 1929. Serial No. 352,170.

This invention relates to floating roofs for liquid storage tanks.

One object of my invention isto provide a floating roof for'liquid storage tanks that is-equipped with a combined rain shield and sun shade structure of novel construction, which effectively prevents the roof from he'- ing sunk, due to the accumulation thereon of an excessive 'load of rain water, and which produces a ventilated space over the roof" through which air circulates in such a man her as to effectively remove or carry away heat that radiates from the roof,

Another object'is to provide a trussedfloating roof of the pan type, that is equipped with a rain shield or sun shade constructed of light weight sheet material and supported entirely or partially by some of the truss members of the roof.

Another object is to provide a floating tank roof for liquid storage tanks, that is equipped with a drainage means which is constructed in such a way that it will be impossible for liquid in the tank to back up in the drainage system and escape onto the top surface of the roof.

Another object is to provide a floating tank roof of the pan type, which is equipped with a rain shield and drainage system, so constructed and arranged that in the event the drainage system breaks or becomes clogged, the rain water which falls on to the rain shield will be discharged into the tank, instead of onto, the top surface of the roof, thereby eliminating the possibility of the roof sinking, as might occur if an abnormal load or rain water collected in the same,-

Another object is to provide a floating zank roof in which the means used to seal the space between the peripheral edge .of the cot and the side Wall of the tank comprises L trough that normally contains rain water vhich has been discharged into said trough rom a rain shield that covers the roof.

And still another object is to provide a loating tank roof of the pan type, which 5 equipped with a rain shield from which ain water is conducted by drain pipes iounted on the top side of the roof and aranged so that they constitute part of a truss which is used to reinforce and strengthen the roof. Other objects and desirable features of my invention will be hereinafterpointed out. w

Figure 1 of the drawing is a vertical transverse sectional view of a floating tank roof constructed vention; and I Figure 2 is a top plan view, partly broken away, of the structure shown in Figure 1.

In the accompanying drawing which illustrates the preferred orm of my invention. A designates the side wallof a tank that is used for storing oil or other liquids, and B designates a floating roof of the pan type that rests upon or floats on the liquid in the tank and which is provided at its peripheral edge with a vertically-disposed rim C of annular form that is arranged in spaced relation with the side wall of the tank. The annular space between the rim C and the side wall of the tank may be sealed by any suitable-means; In

in accordance with my in the form of my invention herein illustrated the sealing means just referred to comprises segmental shoe members D carried by the roof and arranged in sliding en agement with the inner face of the side wal A, and a flexible member E, usually a piece of gas-tight fabric, that is attached to the rim C and to the upper edge portions of the shoe members D. Said shoe members are mounted on the roof B in such a way that they can move inwardly and outwardly relatively to same so as to prov de for the expansion and contraction of the-slde wall of the tank and still remain in sliding engagement with the inner face of said side wall. I have herein illustrated the shoes D as beingsupported from the rim 0 by sprlng hangers F that force said shoes outwardly towards the side wall of the tank, but I WlSh It to be understood that varioustypes and kinds of means may be used to seal or substantially seal the annular space at the peripheral edge of the roof, without departing from the spirit of my invention.

The roof B is provided with a truss formed preferably by a center post or strut G from the upper end of which rods H extend radially to the rim C to which they are firmly connected, said rods H sloping inwardly and upwardly from the rim C and being attached at their inner ends to a plate l arranged at the upper end of the center "post G. If desired,

radially-disposed truss members I may be attached to'the top side of the roof B, and inclined braces or gusset plates J can be attached to the truss members I and to the rim C, so as to resist the strains which the truss rods H exert on the rim in a direction tendinglto deflect said rim C inwardly.

order to protect the roof from the direct action of the suns rays, and also prevent rain water from falling onto and remaining on the roof, I have equipped the roof B with a rain shield and sun shade K, whichis of such construction and arrangement that air will circulate through the space between the member K and the roof, and thus e'fi'ectively re- 1 move heat or heated air from said space, and

rain that'falls on said shield K will be discharged automatically from same into an annular trough located at the peripheral edge of the roof. The combined rain shield and sun shade K is constructed from light-weight sheet material, such as thin sheet metal, and

while it may .be sustained or supported in various ways, prefer to sustain it at least partly by the truss rods H of the roof. In the form of my invention herein illustrated the rain shield and sun shade K is of substantially conical shape in general outline, and the peripheral edge of same rests upon and is connected to the rim 0 of the roof. The member K can be constructed and arranged in a any way'that will permit or cause air to circulate through the space between said member and the roof, but I prefer to provide the member K withventilators K, arranged adjacent itscenter and adjacent its peripheral edge so as to form an air outlet at or adjacent to the center of the member K that is located in a higher horizontal plane than the inlet or inlets through which the air enters, thereby producing in effect an air siphon which effectively removes the air from thespace between the roof and the shield K when the air in said space becomes hotter than the air above the shield K.

The trough previously referred to that is arranged at the peripheral edge of the rain shield K so as to receive or collect the rain I water that falls onto said shield, is preferably formed by the fabric member E, previou'sly mentioned, that constitutes part of the seal between the floating roof and the side wall of the tank. The rim C of the roof to of a trough that completely surrounds the rain shield K and which is arranged in such relationship with same that it will receive the rain Water which discharges from the peripheral edge of said shield. As the collection trough E is arranged beyond or outside of the T peripheral edge of the floating roof,- said trough acts as a protecting device for the 11(1 uid in the tank that lies between the rim of the floating roof and the side wall of the tank. Consequently, I trough E so that it will normally hold or contain a body of water which acts as an insulator to keep thespace under the peripheral sealing means of the roof relatively cool, and thus cut down evaporation. Another object in using a trough E that is capable of holding a considerable quantity of water is that said trough of itself constitutes a drainage means that has sufiicient capacity to take care of. a light rain fall, and which, in the event of a heavy rain fall, will discharge either outwardly from the top edge of the outer wall of the trough, as hereinafter explained, or discharge into drain pipes L that are attached to the inner wall of the trough adjacent the upper edge of said inner wall, and which incline downwardly from said trough to a sump M which is arranged at the center of the roof on the top sideof same. The sump M is rovided with an overflow pipe N that pro ects downwardly through the roof B and which is connected to the upper end of a piece'of flexible tubing 0 Whose lower end is attached to an inclined drain pipe P on the bottom of the tank which leads outwardly through the side wall of the tank, as shown in Figure l, the flexible tubing 0 being long enough toprovide for the vertical movement of the roof 13 pro-' duced by variations in the level of the liquid in the tank. The drain pipes L on the top side of the roof may either be straight and.

inclined upwardly and outwardly from thesump M to the rim C to which the outer ends of said pipes L are attached, or said pipes may comprise straight portions attached directly to the top side of the roof B and branching radially from the sump M and provided at the outer ends with upwardly-inclined portions which are attached to the rim C adjacent the top edge of said rim. The pipes L virtually form truss members for the roof, and while they have herein been illustrated in conjunction with truss members I and J, it is possible in tanks of small size, say, for example, 50 ft. in diameter, to omit the truss members I and J and rely upon the drain pipes L to take up the thrusts or strains which the truss rods H exert on the rim 0 of the roof.

In a structure of the kind above described rain water which falls on the shield K will collect in the trough at the peripheral edge of said shield, and subsequently, the major.

portion of the rain water will be discharged from said trough through the drain pipes L prefer to construct the a into the sump M, finally escaping from said sump the pipe N and tubing into the outlet pipe or discharge pipe E on the bottom oi V the outer wall of the trough, i. e., over the top edge of the shoe members D, downwardly into the tank, it being impossible for rain water to rise high enough in the sump M to flow over the top edge of same, due to the fact that the top edge of the sump terminates at a point above the collection trough at the peripheral edge of the rain shield K. Nor is itpossible for rain water to escape from said trough by flowing over the top edge of the inner wall of said trough, i. e., the wall formed by the rim C, due to the fact that the top edge of the rim C terminates at a point higher than the top edge of the shoemembers D. In the event the portion of the drainage system located on the inside of the tank breaks or develops aleak, there is no danger of liquid in the tank backing up in thedrainage system 'and overflowing onto the top surface of the roof, due to the fact that the upper end of the outlet pipe N leading from the sump M, terminates at a point higher than the level of the liquid in the tank on which the roof floats.

A pan type'floating roof of the construction above described, even when used in a tank having a diameter in excess of ft, is strong enough to successfully withstand strains to which it is subjected when in service, due to the eflicient manner in which it is trussed; it is not liable to become overheated or excessively heated in hot weather, due to the fact that it is protected .from the direct .rays of the sun by a shield under which there is a constant circulation of air; it is relatively inexpensive to construct, due to the fact that the rain shield or sun shade is sustained principally by the truss members of the roof and the rain collection trough at the peripheral edge of the shield is formed by the structure that closes the annular space between the roof and the side wall of the'tank; and it is of such design that it is impossible for rain water or liquid in the tank to collect on the top side of the roof in a suflicientquantity to sink the roof.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A floating roof forliquid storage tanks, provided with a shield carried by the roof and arranged so that it slopes upwardly from the peripheral edge of the roof, and a drainage system for effecting the removal of rain water that falls on said shield, comprising means for preventing rain water or the liquid in the tank on which the roof floats, from collecting on the top side of. the roof in a suflicient quantity to sink the roof. I f

2. A floating roof for liquid storage tanks, provided with a shield carried by the roof and arranged to cover substantially the entire .area of same, and a rain'collection trough at the peripheral edge of said shield formed-by a structure that serves as a closure for the space between the roof and the sidewall of the tank. r

3. A floating roof for liquid storage tanks, provided with a shield carried by the roof and arranged to cover substantially the entire area of same, a rain collection trough at the peripheral edge of said shieldlformed by a structure'that serves as a closure for the space between the roof and the side Wall of the tank, and means for conducting water from said trough into a discharge pipe located on the inside of the tank beneath the roof.

4. .A floating roof for liquid stora e tanks, provided with a rain shield carrie by the roof and covering substantially the entirearea of same, a collection trough adjacent the peripheral edge of the roof for receiving rain water from said shield, and a drainage system leading from said trough, said trough being so constructed and arranged that in the event the drainage system fails or becomes clogged, the water will escape from said trough downwardl into the body of liquid on which the roof oats.

5. A floating roof for liquid storage tanks, a truss for reinforcing and strengthening said roof, comprising truss members arranged on the top side of the roof, a substantially cone shaped rainshield or sun shade arranged in spaced relation with the top side of the roof and resting on said truss members, and a means for permitting air to enter at the outer edge of the space between said roof and shield and circulate inwardly and upwardly through said space. j

6. A floating rooffor liquid storage tanks, a truss for said roof arranged on the top side of-same; a rain shield or sun shade arof t e roof'and resting on said truss, a col lection trough arranged adjacent the peripheral edge of: said shield for receiving rain water from same, and drain pipes leading from said trough that constitute members of I wardly-projecting rim, atruss on the top side of the roof comprising members that slope upwardly from said rim towards the center of the roof, a shield resting on said truss members "and having its peripheral edge ranged in spaced relation with the top side terminating adjacent said rim, a trough surrounding said rim for receiving rain water that'drains from said shield, and means for conducting water out of said trough.

8; A floating roof for liquid storage tanks, provided with a rain shield carried byithe roof and arranged to cover the major porv,tion of the top side of same, a collection trough arranged at the peripheral edge of said shield, a sump on the top side of the roof, means for permitting water to drain from said trough into said sump, and an outlet leading from said sump.

9; A floating roof for liquid storage tanks,

provided with a rain shield carriedby the point higher than'said trough.

10. A floating roof for liquid storage tanks, provided with a rain shield carried by the roof and arranged to cover the major portion of the top side of same, a collectiontrough arranged at the peripheral edge of said shield,'a sump on the top side of the roof,

means for permitting water to drain from said trough into said sump, and an outlet leading from said sump, the outlet from said sump having an intake which is located in a horizontal plane higher than the level of the liquid in the tank on which the roof floats.

11. A floating roof for liquid storage tanks, provided at its peripheral edge with an up- -wardly-projecting rim, a substantially gastight closure for the space between said rim and the side wall of the tank, constructed so as to form a water collection trough that surrounds said rim and which is located at a point below the top edge of same, a rain shield carried by the roof and arranged so that water which drains from same will enter 7 said trough, and means for conducting .water from said trough to a discharge pipe located in the tank on the underside of the roof.

12. A floating roof for liquid storage tanks,

provided at its peripheral edge with an upwardly-projecting rim, a substantially gas-1 tight closure for the space between said rim and the side wall of the tank, constructed so as to vform a water collection trough that.

surrounds said rim and which is located at a point below the top edge of same, a. rain shield carried by the roof and arranged so that water which drains from same will en-' ter said trough, a'suinp on the top side of the,

roof having a side wall whose top edge ter minates at a point higher than said trough,

- drain pipes leading from said trough to said sump, and an outlet pipe in said sump connected with a discharge pipe arranged inside of the .tank, the intake of said outlet pipe being located at a point higher than the level of the liquid in the tank on which the roof floats. v

13. A floating roof for liquid storage tanks, provided at its peripheral edge with an upwardly-projecting rim, a center post on the top side of the roof whose upper end terminates at a point higher than the top ed e of said rim, truss members attached to said center post and to the upper edge portion of said rim, a substantially conical shaped shield sustained by said rim and truss members, a closure for the space between said rim and the side wall of the tank provided with I 14. The combination of a. tank adapted to hold a liquid, a roof that floats on the liquid in the tank and having its peripheral edge spaced away from the side wall of the tank,

.a shield carried by theroof and arranged so that it slopes upwardly from the peripheral edge of the roof, and a sealing means forthe space between the roof and the side wall of the tank, comprising a trough arranged so as to receive rain water that discharges from the outer edge of said shield.

15. A structure of the kind described in claim 14, providedwith means for inducing or permitting a'circulation of air throu h the space between the floating roof; an said shield.' g

16, A floating roof for a liquid storage tank provided with a shield carried by the roof and arranged to cover substantially the entire area of same, said shield sloping upwardly from the outer edge of the floating roof, and means for closing the space between the roof and the side wall of the tank, comprising a rain collection trough arranged adjacent the peripheral edge or discharge edge of said shield.

17. A floating roof for a liquid storage tank having mounted thereon a shield that is arranged in spaced relationship with the roof, the central portion of said shield being higher than its peripheral portion 'and said shield being provided adjacent its center and adja;-

roof adapted to receive rain water discharged 'from said shield, and-a drain pipe for said trough entering the same at a point above the bottom of the trough, whereby a certain amount of rain water received by said trough,

same.

will be retained in JOHN H. WIGGINS. 

